1. Field of the Invention
This invention relates to a method of making high performance explosive compositions that are pressable or extrudable and suitable for high performance, low sensitivity explosive applications. More specifically, this invention relates to a method of making high performance explosive compositions containing CL-20 as an explosive ingredient, non-energetic polymeric binders and plasticizers.
2. Description of the Related Art
Among the litany of high performance explosives that have been used in ordnance and other high impact applications, a relatively new explosive known as CL-20 has been recognized for its superior energy levels that far surpass those of most conventional explosives. CL-20 is also referred to commonly as (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo [5.5.0.0.sup.5,9.0.sup.3,11 ]-dodecane and 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane.
Examples of explosive formulations containing CL-20 as the primary explosive component are disclosed in both U.S. Pat. No. 5,587,553 to Braithwaite et al. and U.S. Pat. No. 5,712,511 to Chan et al. As touched upon in the Chan et al. '511 patent, which relates to explosive compositions for deformable-type warheads and directional ordnances, CL-20 is extremely sensitive to physical impact. Indeed, CL-20 has been associated with high electrical and thermal sensitivities as well. The highly sensitive nature of CL-20 may lead to premature detonation in ordnance applications. The Chan et al. patent apparently compensates for the high sensitivity of CL-20 by incorporating it into high energy shock-insensitive explosive compositions comprised of a relatively low concentration of CL-20, e.g., from about 35 wt % to about 45 wt %.
In contrast, the Braithwaite et al. patent seeks to improve the high performance of the CL-20 explosive by using it in high concentrations and in combination with high molecular weight liquid energetic polymers, especially chain-extended polyglycidyl nitrate (PGN). It has also been known to use CL-20 in combination with other energetic polymers. One such combination commonly known as LX-19 and available from Thiokol Corporation, Inc., now Cordant Technologies, Inc., combines CL-20 with ESTANE (C.sub.5.14 H.sub.7.5 N.sub.0.187 O.sub.1.76). LX-19 is made by a water slurry process. The performance characteristics, e.g., energy levels, exhibited by LX-19 are generally considered to be excellent. However, the impact, electrical, and thermal sensitivities associated with LX-19 and other formulations using CL-20 in combination with energetic binders are considered to be too high for some applications.
It would, therefore, be a significant advancement in the art to provide a method of making a plastic bonded explosive formulation that contains a sufficient amount of CL-20 to exhibit equal or better high energy performance than LX-19, yet which has sufficiently low impact, electrical, and thermal sensitivities to permit the formulation to be used for a variety of applications without an unacceptable risk of unintentional or premature detonation.